1. Field of the Invention
The present invention relates to a complex head consisting of a reading head making use of a magnetroresistance effect and an inductive recording head. The complex head is used for, for example, a magnetic recording and reproducing apparatus.
2. Description of the Prior Art
Heretofore, there is a tendency that a size of a record bit on a magnetic record medium rapidly becomes small in size as magnetic record mediums become small in size and vast in capacity. In order to deal with such tendency, a magnetroresistance effect type head (hereinafter, referred to as xe2x80x9cMR headxe2x80x9d) which has a high-level output has been put to practical use. An MR head is discussed in xe2x80x9cA Magnetroresistivity Readout Transducerxe2x80x9d (IEEE Transaction on Magnetics, MAG 7 (1971), p.150).
FIGS. 1A, 1B, and 2 show magnetroresistance effect type complex head (hereinafter, referred to as xe2x80x9cMR complex headxe2x80x9d) consisting of an MR head for reading and an inductive head (hereinafter, referred to as xe2x80x9cID headxe2x80x9d) for recording as a first prior art. FIG. 1A is a plan view, FIG. 1B is a cross-sectional view taken along line A-Axe2x80x2 in FIG. 1A, and FIG. 2 is a front elevation. FIG. 2 is taken from the left of FIG. 1A or 1B. A plane shown in FIG. 2 confronts a record medium and referred to as an air-bearing plane.
Referring to FIGS. 1A and 1B, members indicated by reference numerals 31 and 32 are insulators, a number indicated by reference numeral 33 is a coil pattern. Coil pattern 33 is visible in FIG. 1A because insulator 31 is semi-transparent.
Referring to FIG. 2, the MR head comprises two face-to-face magnetic shield films S1 indicated by 10 and S2 indicated by 17, magnetic separators 11 and 16 comprising insulators, and magnetroresistance effect element (hereinafter, referred to as xe2x80x9cMR elementxe2x80x9d) 15 disposed between magnetic shield film S1 (10) and magnetic shield film S2 (17) with interposition of magnetic separators 11 and 16. The ID head comprises a magnetic pole film P1 indicated by 17, magnetic pole film P2 indicated by 19, and magnetic gap 18. Therefore, the portion indicated by 17 is magnetic shield film S2 as well as magnetic pole film P1.
The MR complex head causes a considerably strong side fringe magnetic field while recording. This side fringe magnetic field is caused by a leakage of a magnetic flux to a portion of magnetic pole film P1 (17) over a width of magnetic pole film P2 (19) because magnetic pole film P1 (17) is wider than magnetic pole film P2 (19). This side fringe magnetic field restricts an allowable minimum track width and therefore a track density. Therefore, it is necessary to reduce this side fringe magnetic field in order to attain a high-density magnetic recording with an MR complex head.
A conventional ID head for recording/reading caused a weak side fringe magnetic field because the conventional ID head was so designed that a lateral side of magnetic pole film P1 and a lateral side of magnetic pole film P2 are substantially disposed on a same plane at and near to an air bearing surface at both lateral sides. The lateral sides determines a track width. On the other hand, as to an MR complex head, magnetic pole film P1 (17) is considerably wider than magnetic pole film P2 (19) of which width determines a track width because magnetic pole film P1 (17) needs to have a function to shield an MR element 15. This difference in width causes a side fringe magnetic field which extends over a width of magnetic pole film P2 (19) laterally.
A second prior art is an MR complex head disclosed in JPA 7-262519 and shown in FIG. 3, and it causes as weak a side fringe magnetic field as an ID head. Referring to FIG. 3, the second prior art MR complex head comprises magnetic pole film P3 which is indicated by 17xe2x80x2. Magnetic pole film P3 (17xe2x80x2) is disposed between magnetic pole film P1 (17) and magnetic gap G (18) and parallel to a surface of magnetic pole film P1 (17), and magnetically continues with magnetic pole film P1 (17). Each of two lateral sides of magnetic pole film P3 (17xe2x80x2) is disposed on the same plane with each of two lateral sides of magnetic pole film P2 (19) which determines a width of magnetic pole film P2 (19). Also, each of two lateral sides of magnetic pole film P3 (17xe2x80x2) is perpendicular to a surface of magnetic pole film P1 (17). On such structure, a magnetic field for recording is caused between magnetic pole film P2 (19) and magnetic pole film P3 (17xe2x80x2), and therefore a side fringe magnetic field is suppressed as a conventional ID head.
The method for manufacturing magnetic pole film P3 (17xe2x80x2) is shown in FIG. 4. Referring to FIG. 4, magnetic gap G (18) is formed on magnetic pole film P1 (17) which is also used as a magnetic shield S2 of an MR head. Then, a coil insulated by a photoresist is formed. Then, magnetic pole film P2 (19) having a prescribed width is formed by frame plating process with restriction by photo resist frame 23. Then, magnetic pole film P3 (17xe2x80x2) is formed to a desired edged depth by an ion beam milling using magnetic pole film P2 (19) as a mask. When forming magnetic pole film P3 (17xe2x80x2), it is possible to make lateral sides of magnetic pole film P2 (19) and P3 (17xe2x80x2) perpendicular to an upper surface of magnetic pole film P1 (17). By setting a depth of magnetic pole film P3 (17xe2x80x2) to the desired value, a recording magnetic flux is substantially restricted by magnetic pole films P2 (19) and P3 (17xe2x80x2), and therefore a side fringe magnetic field is suppressed as a conventional ID head.
As explained above, in the method for manufacturing the MR complex head according to the second prior art, the ion beam milling is heavily used for forming magnetic pole film P3 (17xe2x80x2). A thickness of magnetic pole film P2 (19) decreases as the milling continues because magnetic pole film P2 (19) serves as a mask during the milling. Therefore, an initial thickness of magnetic pole film P2 (19) must be set in consideration of the decrease due to the milling in order to obtain a desired final thickness of magnetic pole film P2 (19). In addition, in the method for manufacturing the MR complex head according to the second prior art, a height of frame 23 must be set considerably high as compared to a conventional method for forming initial magnetic pole film P2 (19) by the frame plating process. That is, magnetic pole film P2 (19) before the milling must be considerably thick in order to obtain a thickness of magnetic pole film P2 (19) after the milling which ensures recording characteristics because the thickness of magnetic pole film P2 (19) after the milling is considerably decreased as compared with the thickness thereof before the milling. However, if a height of frame 23 is set high in order to form a magnetic pole film P2 (19) of a sufficient thickness, it is difficult to narrow a distance between two parts of frame 23. The lower limit of the distance between the two parts of frame 23 is 2 xcexcm in the second prior art. That is, it was difficult to manufacture an MR complex head which realizes a high recording density of a track width of under 2 xcexcm according to the method for manufacturing the MR complex head according to the second prior art.
As explained above, when the structure for reducing a side fringe of a recording magnetic field generated by an ID head is selected for an MR complex head comprising an MR head and an ID head, it paradoxically becomes difficult to manufacture the structure for a narrow track.
One of methods for solving such dilemma is setting a width of magnetic pole film P2 and forming magnetic pole film P3 in combination by a ion beam edging from an air bearing surface during a bar process after having finished a wafer process instead of setting the width of magnetic pole film P2 and forming, on magnetic pole film P1, magnetic pole film P3 having lateral surfaces common with magnetic pole film P2 by a wafer process. This method is a third prior art. FIGS. 5 and 6 show an MR complex head of the third prior art which causes a reduced side fringe of a recording magnetic field from an ID head. Referring to FIGS. 5 and 6, a width of magnetic pole film P2 (19) is determined by pits 20 which are formed by a ion beam edging from an air bearing side executed in a bar process following a wafer process. A projection 17a toward magnetic pole film P2 having lateral sides common with magnetic pole film P2 is also formed in magnetic pole film P1 (17) by the ion beam edging from the air bearing side. Accordingly, a structure for reducing a side fringe magnetic field is easily realized.
FIG. 6 is a perspective view of the MR complex head of the third prior art, and FIG. 7 is a front elevation of a slider with the MR complex head of the third prior art in which numeral 22 stands for a slider and 21 stands for an alumina portion.
A method for manufacturing a thin-film head which comprises an ID head for recording/reading is disclosed in xe2x80x9cEdge Eliminated Headxe2x80x9d (IEEE Trans. on Magn., Vol. 29, No. 6 (1993), 3837) which is a fourth prior art. In the method of the fourth prior art, an ion beam edging from an air bearing surface for configuring a structure which suppresses an undershoot in a reproduced waveform is executed. However, if the method of the fourth prior art is applied to a head for a high-density recording/reading such as an MR complex head comprising an MR head and an ID head, dust accumulates in a pit formed by an ion beam edging, and to the worst the head crashes because a distance between the head and a record medium is extremely short.
An MR complex head which comprises a non-magnetic material inserted into a pit formed by an ion beam edging is disclosed in JPA 10-162315 which is a fifth prior art. An edging using a focused ion beam (FIB) for high-accuracy is also disclosed in JPA 10-162315.
The method for determining a width of magnetic pole P2 (19) and forming magnetic pole P3 (17a) in combination by an ion beam edging from an air bearing surface executed in a bar process after a wafer process is simple and safe. However, the method has a disadvantage of variation of a relational position between an recording ID head of a width determined as mentioned and a reading MR head, which becomes conspicuous as a width of magnetic pole films become narrower than 1 xcexcm. That is, when considering an application of an MR complex head to a magnetic disk drive, if a relational position between an ID head and an MR head does not fall within a certain range, an angle of the ID head deviates from an angle of the MR head when they are positioned at a certain track by a rotary actuator, and accordingly an effective recording/reading can not be executed.
JPA 10-162315 discloses a method for determining a width of magnetic pole film P2 by a focused ion beam, but does not disclose a method for correcting an offset between an MR head and an ID head in connection with positioning pits determining the width of magnetic pole film P2. In practice, it is general that positions of pits are determined with respect to magnetic pole film P2 (19) and then the pits determining a width of magnetic pole films are formed. Therefore, variation caused when positioning the pits determining a width of magnetic pole films as well as variation caused when positioning an ID head on a wafer constitute variation of a position of the ID head with respect to an MR head. Thus, when a width of magnetic pole films becomes narrower than 1 xcexcm so as to be used for a high-density recording, a variation of a relative position between an MR head and an ID head becomes a difficulty, resulting in a decrease in yield rate.
In order to overcome the aforementioned disadvantages, the present invention has been made and accordingly, has an object to provide a magnetroresistance effect type complex head consisting of an MR head and an ID head which has a variation of a relative position between the MR head and the ID head being reduced to be negligible as compared with a with of magnetic pole films less than 1 xcexcm to meet a specification of an ultra high-density magnetic recording/reproducing apparatus notwithstanding the head is produced by a process which includes a step of determining a width of magnetic pole films from an air bearing surface. Another object of the present invention is to provide a method for manufacturing such magnetroresistance effect type complex head with a high yield rate.
According to a first aspect of the present invention, there is provided a magnetroresistance effect type complex head comprising: (1) a magnetroresistance effect head comprising: a magnetroresistance effect element comprising a central region for detecting a magnetic field from a record medium and a pair of terminal portions for supplying a bias magnetic field and a current to the central region; a pair of magnetic separators confronting each other, sandwiching the magnetroresistance effect element, and each comprising an insulator; and a first and second magnetic shield films confronting each other, and sandwitching the magnetroresistance effect element and the pair of magnetic separators; (2) an inductive head using the second magnetic shield as a first magnetic pole film; and comprising a magnetic gap piled up on the first magnetic pole film; a second magnetic pole film piled up on the magnetic gap; and a coil pattern for generating a magnetic flux which flows through the first and second magnetic pole films; (3) a pair of pits digged in a direction perpendicular to an air bearing surface and disposed on both lateral sides of the second magnetic pole film to determine a width of the second magnetic pole film; and (4) a pattern for determining a position of the pair of recesses.
The pattern may be formed of recesses formed in the first magnetic shield.
Each of the recesses may be disposed under each of the pair of terminal portions.
Each of the recesses may be disposed under a outwardly and laterally extended position from each of the pair of terminal portions.
A width of the second magnetic pole film may be less than 1 xcexcm.
The first magnetic pole film may have a pair of recesses where the pair of pits invade so that a third magnetic pole film projecting toward the second magnetic pole film and having a width as same as the second magnetic pole film is formed.
According to a second aspect of the present invention, there is provided a method for manufacturing a magnetroresistance effect type complex head comprising steps of: providing a wafer; forming a first magnetic shield on the wafer; forming an alignment mark and a pattern on the first magnetic shield using a single photomask; forming a magnetroresistance effect element on the first magnetic shield using the alignment mark as a reference of a position; forming a second magnetic shield which also functions as a first magnetic pole film on the magnetroresistance effect element; forming a gap on the second magnetic shield; forming a second magnetic pole film on the gap; cutting out a bar from the wafer; polishing the bar from an air bearing surface; and forming a pair of pits from the air bearing surface to determine a width of the second magnetic pole film using the pattern as a reference of a position.
The method may further comprise steps of: cutting out a chip from the bar; and assembling the chip to a suspension.
At the step of forming the pair of pits, the pair of pits may be formed so that the pair of pits generates a third magnetic pole film which has lateral sides common with the second magnetic pole film in said second magnetic shield.
At the step of forming the pair of pits, the pair of pits may be formed by a ion beam edging method.
The ion beam edging method may be executed using a focused ion beam.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of the best mode embodiments thereof, as illustrated in the accompanying drawings.